The possibilities for use of mechanical components, in particular mechanical gearwheels, in the field of mechanical engineering are practically endless. When considering the category of gearwheels by way of example, these often have to be produced with considerable manufacturing effort, for example by machining a solid body.
An alternative to machining is provided by the possibility of forming by cold, warm, and hot lateral extrusion or upsetting, in which a component is compressed along a first spatial direction by the application of considerable compressive forces, wherein, due to this compression, the material flows into cavities which are provided by a tool transverse to the first spatial direction. A method of this type is described, for example, in DE 37 18 884 A1.
The approach described in DE 37 18 884 A1 is only applicable, however, to a limited number of preforms to be formed, since a considerable amount of pressure has to be exerted onto the component along the direction of compression to achieve the lateral extrusion process. If, however, contrary to the teaching of DE 37 18 884 A1, a preform formed from a solid material is not inserted into the tool, but instead a thin-walled hollow body, for example, a tube portion or a beaker-shaped hollow body is to be formed, the dimension of the structure which is provided by the tool through the cavities and which is to be filled with material by the lateral extrusion process, is extremely limited. The reason for this lies primarily in the fact that the larger the structure to be filled, the greater the risk of buckling of the thin wall of the preform in the region of the structure at the start of the forming process. In accordance with the invention, only thin-walled preforms in which the available wall height of the preform x is at most 2.3 times the initial wall thickness t1 can therefore be used for the production of components of this type. Otherwise, there is a risk of buckling, which has serious effects on the properties of the component produced.
DE 34 09 549 A1 describes a method for producing flanges or collars on hollow parts by lateral extrusion, wherein the material is supported in the hole during the extrusion process by a plastically acting tool. The disadvantage of this method lies in the use of a hollow body as a preform, which is merely to be used for the production of a structure of limited dimension and, in addition, cannot produce a precisely defined geometry with the plastic support body.
DE 1 087 433 B describes the production of a hub body for freewheel brake hubs formed from a seamless tube portion by cold extrusion. In this case, too, the disadvantage is the production of a structure (spoke flange) of limited dimension due to the use of a hollow body as a preliminary workpiece (preform) without use of a support element.